This invention relates to radar systems, and more particularly to a radar antenna suited for foliage penetration.
The Government has a requirement for an ultra wide band foliage penetration antenna for a radar to detect targets concealed in a forest. The antenna requirements include 1) ultra wide band, 4:1 ratio UHF frequencies, 2) compact, to fit in a very shallow (50 cm) radome mounted in the belly of an aerial surveillance vehicle, 3) dual linear polarizations, V- and H-polarization, 4) well matched to have an input VSWR less than 2:1 over 90% of the band, 5) side-looking beam pointed at 30-degree depression angle, 60 degree from the nadir, and 6) high power, at relatively high altitudes.
This invention is addressed to this particular application, although the invention can be employed in other applications.
A radar antenna is described, and includes a vertical polarization subarray of vertical polarization radiating elements, including a first plurality of vertical polarization element slabs each carrying a second plurality of the vertical polarization radiating elements. The antenna also includes a horizontal polarization subarray of horizontal polarization radiating elements, including a third plurality of horizontal polarization element slabs each carrying a fourth plurality of the horizontal polarization radiating elements. The vertical polarization element slabs and the horizontal polarization element slabs are interleaved into generally transverse spaced relation to provide a reticulated compartmented structure.